Fluid pressure switch



Feb. 26, 1957 w. E. BROWN ETAL 2,783,324

FLUID PRESSURE SWITCH Filed Aug. 3, 1954 INVENTOR. William E. Brown aro/d V. Ell/off Af/ome y FLUID PRESSURE SWITCH Application August 3, 1954, Serial No. 447,507

Claims. (Cl. 200-83) This invention relates to fluid pressure switches and more particularly to an improved switch structure that is adapted to make or break an electric circuit in response to variations in fluid pressure in a fluid system.

The switch according to the present invention is particularly adapted for use in connection with a remotely located signal light such as may be mounted on the dashboard of a vehicle and which is closed when the oil pressure of the engine is less than a predetermined value. Switches of this type are generally constructed to break the circuit to the lamp when the oil pressure of the engine rises above some predetermined value; and to make the circuit when the oil pressure falls to some value less than a calibrated predetermined value, due to failure in some part of the system or other causes, and cause the indicating lamp to burn and warn the operator of the vehicle of the failure of some part of the oil pressure system.

It is an object therefore of the present invention to provide a fluid pressure switch with a means for limiting the movement of a flexible diaphragm and a means for controlling the escape of fluid from one side of the diaphragm when the diaphragm is moved in response to pressure fluctuations on its other side.

it is another object of the present invention to provide a fluid pressure switch with a solid flexible diaphragm which divides the switch housing into two chambers, one of which is connected to a source of pressure and the other is connected to a source of lower fluid pressure through an opening that is calibrated for a predetermined fluid flow by a plug which normally partially closes the opening during normal operation of the switch and which completely closes the opening in event the diaphragm is ruptured.

it is a further object of the present invention to provide a fluid pressure switch with a solid flexible diaphragm that divides a switch housing into two chambers, one of which is connected to a source of variable fluid pressure and the other is connected with a source of lower fluid pressure through an opening calibrated for predetermined flow by a plug that closes the opening in event the diaphragm is ruptured; and wherein the plug is integrally formed on an insulated sleeve that carries an enlargement of a stationary contact on its end which limits the range of movement of a movable contact and thereby reduces the possibility of rupture of the diaphragm during periods when the diaphragm is subjected to excess fluid pressure.

it is still a further object of the present invention to provide an insulating sleeve in a fluid pressure sensitive switch to position a stationary contact so that it acts as a stop for a movable contact and wherein the sleeve has a plug integrally formed and resiliently carried thereon which plug acts as a calibrating means for a vent opening in the switch housing and which closes said opening in event of rupture of the pressure sensitive diaphragm.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a ire States Patent 0 preferred embodiment of the present invention is clearly shown.

In the drawing:

Figure 1 is an end view of a switch according to the present invention.

Figure 2 is a sectional view taken along line 22 of Figure 1 showing the switch in a circuit closing position.

Figure 3 is an enlarged broken away view of a portion of the switch shown in Figure 2 wherein the switch parts are in an open circuit position.

Figure 4 in perspective shows an insulating sleeve with the vent hole plug integrally formed thereon.

Referring to the drawing the numeral 20 designates a fluid pressure sensitive switch which is adapted to control the operation of an indicator or lamp 222 in accordance with the pressure as developed at a source, such as in the lubricating system of an internal combustion engine, not shown. The switch 20 is constructed to complete an electrical circuit between terminal 24 and a fitting 26 which is suitably grounded so that when the pressure at the source is less than a calibrated predetermined value the lamp 22 will be illuminated and thus indicates at a remote point one of the conditions of the fluid system.

Referring to Figures 2 and 3 of the drawings, the switch 2t? includes a housing 23 which is divided into a high pressure chamber 30 and a low pressure chamber 32 by a flexible diaphragm 34 of elastomeric or other suitable material which is preferably resistant to the attack of lubricating oil.

The periphery of diaphragm 34 is clamped between a flange 36 of shell 38 and an outwardly extending flange 40 of shell 42 when the flange 40 is bent around flange 36 as clearly shown in the drawing to seal the chambers 3d, 32 from each other. The fitting 25 which is secured in shell 42 of the switch housing 28 in any well known manner, is connected with a source of fluid pressure, not shown, to transmit the pressure of the source to chamber 30 and cause the diaphragm 34 to be flexed into chamber 32 as partly defined by shell 33 which forms another part of the switch housing 28. Shell 38 has an opening 44 which acts as a vent opening and exposes chamber 32 to a source of lower pressure, such as atmospheric pressure. This opening 44 is partially closed by a tapered plug 46 which is or" a slightly smaller diameter than opening 44 and is integrally formed and resiliently mounted on a sleeve 48 by a flexible hinge portion 50. The hinge 50 is constructed to position the plug 46 in opening 44 to calibrate the flow or" venting fluid through the opening 44 when the diaphragm moves in response to pressure variations in chamber 30.

The material and shape of the sleeve 48, the plug 46 and hinge portion 50 is of a suitable insulating material, preferably nylon, and is clearly shown in Figure 4. The hinge portion 50 normally maintains plug 46 in the center of opening 44 and because of the relation in size and shape of the plug 46 and the opening 44, the opening is normally in an open position to permit fluid to pass between the peripheries of the plug 46 and opening 44. This calibrated vent opening 44 reduces the hysteresis of diaphragm 34 as it responds to the pressure variations in chamber 3!). The plug 46 also has its root portion tapered so that in the event or" rupture of diaphragm 34, the fluid under pressure in chamber 30 will rush into chamber 32 and exert a sullicient pressure on the base of plug 46 to cause the plug 46 to swing on hinge 50 and force it into tight sealing engagement with hole 44 and thus prevent the escape of fluid to the exterior of the housing 28. In this connection it is to be noted that because of the resilient type of binge arrangement 50, the plug 46 will vibrate to a minor degree when the vehicle is in motion and constantly maintain the vent hole 44 open when the switch is subjected to dust or other matter which would otherwise seal the opening 44.

The sleeve 48 extends through an opening 51 in shell 38 and is maintained in complete sealing engagement with the shell 38 by an insulated washer 52 which is held in place by a metallic washer 54. This washer 54 in turn is held in position by the staked portions 56 of terminal 24 which is a part of a stationary contact 58. Contact 58 extends coaxially through the insulating sleeve 48 from the exterior of housing 28 into the lower pressure chamber 32. The stationary contact 58 has an enlarged end 60 which is normally spaced from diaphragm 34 and radially projects beyond the outer surface of sleeve 48. This enlarged end 60 acts as a stop for a movable contact 62. Contact 62 is annular in shape and provides a seat for one end of compression spring 64 which has its other end seated on the inner wall of shell 38 to constantly urge the movable contact 62 into engagement with diaphragm 34. The end 60 of contact 58 is constructed and arranged relative to an extending flange 66 on contact 62 to limit the movement of the contact 62 by spring 64. This restriction of the movement of contact 62 by end 60 limits the stress that is placed upon diaphragm 34 when the pressure within chamber 30 falls beneath the predetermined value as is determined by the calibration of spring 64. The sleeve 48 also has a collar 59 integrally formed thereon. This collar 59 is engaged by and will limit the movement of the contact 66 to the right and prevent engagement between the plug 46 and the contact 66. This will prevent the plug from being jammed in hole 44 in event the diaphragm is subjected to excess pressure.

From the foregoing it is apparent that after the engine is started, and the oil supply is adequate, the engine driven oil pump will build the pressure within chamber 30 to a value suflicient to move diaphragm 34 to the left as in Figure 2 whereby flange 66, which loosely embraces the sleeve 48, moves from its engagement with the end 60 of stationary contact 58, to a position as shown in Figure 3 of the drawing. This movement of the flange 66 from end 60 of contact 58 will cause an electric circuit including; terminal 24, contact 58, flange 66 of the movable contact 62, spring 64, shell 38, shell 42, fitting 26, ground 70 and battery 69 to be broken so that the lamp 22 will be disconnected from the circuit.

From the above it is apparent that the opening 44 is constantly being maintained open because of the relative size of plug 46. This vent opening is provided to insure the maintenance of a predetermined pressure such as atmospheric pressure within chamber 32, irrespective of the movements of the diaphragm 34 or temperature changes of the various component parts of the switch 2d. The spring 64 is so constructed that the switch 20 will open at a minimum engine oil pressure. 30 long as the lamp 22 does not burn, the oil pressure is adequate. When the amount of oil in the crankcase of the engine is too low for safe operation of the engine, the pressure against diaphragm 34 will fall below a predetermined value, p. s. i., for example, and the spring 64 will cause the contact 62 to move to the right as in the drawings to engage contact 53 and cause the lamp 22 to be connected in circuit and burn to indicate to the operator of the motor vehicle that the oil should be added to the crankcase or the pressure of the oil pressure system should be checked and serviced.

Manifestly the switch according to the present invention may be utilized in connection with fluid pressure systems other than those connected with internal combustion engines and further while the present switch is shown to make a circuit upon decrease in pressure, the parts of the switch, including the arrangement of the contacts, could be modified to make a circuit upon an increase in pressure without departing from the scope of the present invention.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a fluid pressure switch, the combination comprising a, flexible diaphragm dividing a switch housing into two chambers wherein one of said chambers is sealingly connectable to a source of variable fluid pressure and the other chamber is adapted to communicate with a source of lower fluid pressure through an opening in said housing, a valve means resiliently mounted in said other chamber having a cylindrical portion within said opening constructed and arranged to normally maintain said open ing partly closed for calibrating fluid flow through said opening and a tapered portion adjacent said cylindrical portion arranged to sealingly close said opening upon rupture of said diaphragm for preventing fluid flow from said source to the exterior of said housing.

2. in a fluid pressure switch having a flexible diaphragm dividing a. switch housing into two chambers wherein one of said chambers is exposed to the atmosphere through a vent hole and the other chamber is adapted to be sealingly connected with a source of variable fluid pressure, the combination comp-rising; a sleeve of insulating material carried by a wall of said housing having one end disposed external to said housing and extending through an opening in said wall into the atmospheric chamber of said housing with the other end thereof in spaced relation to said diaphragm, and a plug integral with and resiliently carried by said sleeve having a cylindrical portion constructed and arranged to normally maintain said vent hole partially closed for calibrating the flow of venting air passing through said hole, said plug also having a tapered portion adjacent said cylindrical portion constructed and arranged for sealingly closing said hole upon rupture of said diaphragm for preventing the flow of fluid from said source to the exterior of said switch housing.

3. In a fluid pressure switch having a flexible diaphragm dividing a switch housing into two chambers wherein one of said chambers is sealingly connectable to a source of variable fluid pressure and the other chamber is in communication with a source of lower fluid pressure through an opening in said housing, the combination comprising; a sleeve of insulating material carried by said housing having one end extending through a second opening therein to the exterior of said housing and having the other end disposed in said other chamber in spaced relation to said diaphragm, a plug integral with and resiliently carried by said sleeve, said plug having; a cylindrical portion constructed and arranged to normally partially close said first opening for calibrating fluid flow through said opening and a tapered portion adjacent said cylindrical portion for closing said opening upon rupture of said diaphragm for preventing the flow of fluid from said source to the exterior of said housing, a movable contact having a portion embracing said sleeve and another portion resting on said diaphragm and a stationary contact having a portion extending through said sleeve to the exterior of said housing and having an enlargement on one end radially extending beyond the other end of said sleeve, said enlarged end being spaced from said diaphragm and arranged to act as a stop for said movable contact and make electric contact therewith when the fluid pressure in said one chamber is less than a predetermined value, and an enlargement on said sleeve for limiting the movement of said movable contact when the pressure in said chamber is greater than a predetermined value.

4. In a fluid pressure switch having a flexible diaphragm dividing a switch housing into two chambers wherein one of said chambers is sealingly connectable to a source of variable fluid pressure and the other chambet is in communication with a source of lower fluid pressure through an opening in said housing, the combination comprising; a movable contact in said other chamber electrically conpected with said housing through a spring that has one end resting on said housing and the other end resting on said contact for urging said contact in one direction and in engagement with said diaphragm, a sleeve of insulating material carried by said housing having one end extending through a second opening in said housing to the exterior thereof and having the other end disposed in said other chamber in spaced relation to said diaphragm and said movable contact, a stationary contact extending from the exterior of said housing through the interior of said sleeve into said other chamber, an enlarged end on said stationary contact normally disposed between said diaphragm and sleeve and radially extending beyond the outer surface of said sleeve, said end being constructed and arranged for limiting the movement of said movable contact in said one direction and making electric contact therewith when the pressure in said one chamber is less than a predetermined value and for limiting the movement of said diaphragm when the pressure in said one chamber exceeds a predetermined value, a plug integrally formed with and resiliently carried by said sleeve, said plug having a cylindrical portion disposed in said first opening and constructed and arranged to normally partially close said first opening for calibrating the fluid flow through said opening and having a tapered portion between said cylindrical portion and said sleeve arranged to sealingly close said opening upon rupture of said diaphragm for preventing the flow of fluid from said source to the exterior of said housing, and an enlargement on said sleeve for limiting the movement of said movable contact when the pressure in said chamber is greater than a predetermined value.

5. In a fluid pressure switch having a flexible diaphragm dividing a switch housing into two chambers wherein one of said chambers is sealingly connectable to a source of variable fluid pressure and the other chamber is adapted to communicate with a source of lower fluid pressure through an opening in said housing, the combination comprising; a sleeve of insulating material carried by said housing having one end extending through a second opening in said housing to the exterior thereof and having the other end disposed in said other chamber in spassd relation to said diaphragm, and a valve means integrally formed with and resiliently carried by said sleeve having a cylindrical portion disposed within said first opening and arranged to normally partially close said first opening for calibrating the flow of fluid passing through said opening from said other chamber, said valve having a tapered portion construed and arranged for sealingly closing said hole upon rupture of said diaphragm for preventing the flow of fluid from said one chamber to the exterior of said housing.

References Cited in the file of this patent UNETED STATES PATENTS 2,202,123 Strode May 28, 1940 2,275,556 Rasmussen Mar. 10, 1942 2,502,326 Koontz et al Mar. 28, 1950 2,512,694 Stout et al June 27, 1950 2,655,573 Szwargulski et al. Oct. 13, 1953 2,661,764 Johnson et al. Dec. 8, 1953 2,698,887 Shaw Ian. 4, 1955 

